Dressing for negative pressure wound therapy with filter

ABSTRACT

Disclosed herein are several embodiments of a wound treatment apparatus employing a wound dressing for negative pressure wound therapy and methods of using the same. Some embodiments are directed to improved wound dressing to be applied to a wound site, for example a wound dressing including a three-dimensional filter element, and methods of using the same.

RELATED APPLICATIONS

This application claims priority to U. K. Provisional Application No.1718014.2, filed Nov. 1, 2017, entitled “DRESSING FOR NEGATIVE PRESSUREWOUND THERAPY WITH FILTER,” the entirety of which is hereby incorporatedby reference.

BACKGROUND Field of the Invention

Embodiments of the present invention relate generally to the treatmentof wounds using negative pressure wound therapy and more specifically towound treatment apparatuses including a wound dressing and a fluidicconnector for use therewith.

Description of the Related Art

The treatment of open or chronic wounds that are too large tospontaneously close or otherwise fail to heal by means of applyingnegative pressure to the site of the wound is well known in the art.Negative pressure wound therapy (NPWT) systems currently known in theart commonly involve placing a cover that is impermeable orsemi-permeable to fluids over the wound, using various means to seal thecover to the tissue of the patient surrounding the wound, and connectinga source of negative pressure (such as a vacuum pump) to the cover in amanner so that negative pressure is created and maintained under thecover. It is believed that such negative pressures promote wound healingby facilitating the formation of granulation tissue at the wound siteand assisting the body's normal inflammatory process whilesimultaneously removing excess fluid, which may contain adversecytokines bacteria. However, further improvements in NPWT are needed tofully realize the benefits of treatment.

Many different types of wound dressings are known for aiding in NPWTsystems. These different types of wound dressings include many differenttypes of materials and layers, for example, gauze, pads, foam pads ormulti-layer wound dressings. One example of a multi-layer wound dressingis the PICO dressing, available from Smith & Nephew, which includes asuperabsorbent layer beneath a backing layer to provide a canister-lesssystem for treating a wound with NPWT. The wound dressing may be sealedto a suction port providing connection to a length of tubing, which maybe used to pump fluid out of the dressing and/or to transmit negativepressure from a pump to the wound dressing.

To provide a canister-less system for treating a wound with negativepressure, a filter to prevent wound fluid from escaping a wound dressingor a suction port and entering a pump, may be required to be included inthe wound dressing or the suction port. At the same time, it woulddesirable that such filter allows uninterrupted air flow such that thenegative pressure from a pump is transmitted to the wound site. However,accumulation of wound fluid under the filter, especially under thenegative pressure, may obstruct air flow through filters, and thuscompromise the benefit of NPWT. Accordingly, there is a need to providefor an improved apparatus, method, and system for filter for thetreatment and closure of wounds.

SUMMARY

Embodiments of the present disclosure relate to wound treatmentapparatuses, wound treatment devices and methods of treating a wound. Insome embodiments of the wound treatment apparatuses described herein, athree-dimensional filter element is utilized with a wound dressingcomprising an absorbent material. Wound treatment apparatuses may alsocomprise a fluidic connector that may be used in combination with thethree-dimensional filter element and the wound dressing describedherein. In some embodiments, a three-dimensional filter element isincorporated into a fluidic connector so that the fluidic connector andthe three-dimensional filter are part of an integral or integratedfluidic connector structure that delivers negative pressure to the wounddressing and prevents wound exudate from escaping from the wounddressing. These and other embodiments as described herein are directedto overcoming particular challenges involved with preventing woundexudate or wound fluid from escaping a wound dressing under negativepressure.

According to some embodiments there is provided a wound treatmentapparatus comprising:

a wound dressing comprising:

-   -   a cover layer comprising an aperture; and    -   an absorbent layer comprising a recess extending vertically        through a thickness of the absorbent layer at least partially,        the absorbent layer positioned beneath the cover layer; and

a fluidic connector configured to provide negative pressure to the wounddressing through the aperture in the cover layer; and

a three-dimensional filter element configured to prevent wound exudatefrom exiting the wound dressing through the aperture of the cover layerwhen negative pressure is provided to the wound dressing, wherein thethree-dimensional filter extends vertically along at least a portion ofthe thickness of the absorbent layer within the recess.

The wound treatment apparatus of the preceding paragraph or in otherembodiments can include one or more of the following features. In someembodiments, the three-dimensional filter element spans the aperture inthe cover layer. The recess may be a through-hole which extends throughthe entire thickness of the absorbent layer. The three-dimensionalfilter element may be at least partially cylindrically shaped orcuboid-shaped. The three-dimensional filter element may have a heightgreater than 3 mm. In some embodiments, the three-dimensional filterelement further comprises a filter layer. The filter layer may beoleophobic. In some embodiments, the three-dimensional filter elementfurther comprises a spacer core, wherein the spacer core is at leastpartially enclosed by the filter layer. The spacer core may comprisecellulose. In some embodiments, the three-dimensional filter element isadhered to the fluidic connector. The three-dimensional filter elementmay extend below the fluidic connector. In some embodiment, the wounddressing further comprises a wound contact layer, a transmission layer,and/or a source of negative pressure.

According to some embodiments there is provided a wound treatmentapparatus comprising:

a wound dressing comprising:

-   -   a cover layer comprising an aperture; and    -   an absorbent layer positioned beneath the cover layer, the        absorbent layer having a thickness;

a fluidic connector configured to provide negative pressure to the wounddressing through the aperture in the cover layer; and

a three-dimensional filter element configured to prevent wound exudatefrom exiting the wound dressing through the aperture of the cover layerwhen negative pressure is provided to the wound dressing.

The wound treatment apparatus of the preceding paragraph or in otherembodiments can include one or more of the following features. In someembodiments, the three-dimensional filter element extends along at leasta portion of the thickness of the absorbent layer. The absorbent layermay comprise a recess extending vertically through a thickness of theabsorbent layer at least partially, and three-dimensional filter elementmay extend vertically along at least a portion of the thickness of theabsorbent layer within the recess. In some embodiments, thethree-dimensional filter element may be above the absorbent layer. Thethree-dimensional filter element may spans the aperture in the coverlayer. The three-dimensional filter element may be at least partiallycylindrically shaped or cuboid-shaped. The three-dimensional filterelement may have a height greater than 3 mm. In some embodiments, thethree-dimensional filter element further comprises a filter layer. Thefilter layer may be oleophobic. In some embodiments, thethree-dimensional filter element further comprises a spacer core,wherein the spacer core is at least partially enclosed by the filterlayer. The spacer core may comprise cellulose. In some embodiments, thethree-dimensional filter element is adhered to the fluidic connector.The three-dimensional filter element may extend below the fluidicconnector. In some embodiment, the wound dressing further comprises awound contact layer, a transmission layer and/or a source of negativepressure.

Other embodiments of an apparatus for use with wound treatment, devices,kits and associated methods are described below.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will be apparentfrom the following detailed description of the invention, taken inconjunction with the accompanying drawings of which:

FIG. 1A illustrates an embodiment of a negative pressure wound treatmentsystem employing a flexible fluidic connector and a wound dressingcapable of absorbing and storing wound exudate;

FIG. 1B illustrates an embodiment of a negative pressure wound treatmentsystem employing a flexible fluidic connector and a wound dressingcapable of absorbing and storing wound exudate;

FIG. 2A illustrates an embodiment of a negative pressure wound treatmentsystem employing a flexible fluidic connector and a wound dressingcapable of absorbing and storing wound exudate;

FIG. 2B illustrates a cross section of an embodiment of a fluidicconnector connected to a wound dressing;

FIGS. 3A-C illustrate various embodiments of the enlarged end of aflexible fluidic connector;

FIGS. 4A-D illustrate the use and application of an embodiment of awound treatment system onto a patient;

FIG. 5A illustrates a top view of an embodiment of a flexible fluidicconnector;

FIG. 5B illustrates a bottom view of an embodiment of a flexible fluidicconnector;

FIG. 5C illustrates a perspective exploded view of an embodiment of aflexible fluidic connector;

FIG. 6 illustrates an embodiment of a flexible fluidic connectorattached to a wound dressing;

FIGS. 7A-B illustrate an embodiment of a flexible fluidic connectorattached to a wound dressing, and another embodiment of a flexiblefluidic connector including a three-dimensional filter element attachedto a wound dressing;

FIG. 8 illustrates a cross-section of an embodiment of a fluidicconnector connected to a wound dressing with a three-dimensional filter;

FIG. 9 illustrates a cross-section of an embodiment of athree-dimensional filter;

FIG. 10A illustrates a schematic view of an embodiment of a fluidicconnector having a three-dimensional filter attached to a wounddressing;

FIG. 10B illustrates a perspective exploded view of the fluidicconnector of FIG. 10A;

FIG. 11A illustrates a schematic view of an embodiment of a fluidicconnector and a wound dressing having a three-dimensional filter.

FIG. 11B illustrates a schematic view of an embodiment of a fluidicconnector and a wound dressing having a three-dimensional filter.

DETAILED DESCRIPTION

Preferred embodiments disclosed herein relate to wound therapy for ahuman or animal body. Therefore, any reference to a wound herein canrefer to a wound on a human or animal body, and any reference to a bodyherein can refer to a human or animal body. The term “wound” as usedherein, in addition to having its broad ordinary meaning, includes anybody part of a patient that may be treated using negative pressure.Wounds include, but are not limited to, open wounds, incisions,lacerations, abrasions, contusions, burns, diabetic ulcers, pressureulcers, stoma, surgical wounds, trauma and venous ulcers or the like.Treatment of such wounds can be performed using negative pressure woundtherapy, wherein a reduced or negative pressure can be applied to thewound to facilitate and promote healing of the wound. It will also beappreciated that the fluidic connector and methods as disclosed hereinmay be applied to other parts of the body, and are not necessarilylimited to treatment of wounds.

Certain embodiments of this application related to a wound treatmentapparatus employing a wound dressing and a fluidic connector, and tomethods of using the same. Certain embodiments of this applicationrelate to a fluidic connector and methods of using the same.

FIGS. 1A-B illustrate embodiments of a negative pressure wound treatmentsystem 10 employing a wound dressing 100 in conjunction with a fluidicconnector 110. Here, the fluidic connector 110 may comprise an elongateconduit, more preferably a bridge 120 having a proximal end 130 and adistal end 140, and an applicator 180 at the distal end 140 of thebridge 120. An optional coupling 160 is preferably disposed at theproximal end 130 of the bridge 120. A cap 170 may be provided with thesystem (and can in some cases, as illustrated, be attached to thecoupling 160). The cap 170 can be useful in preventing fluids fromleaking out of the proximal end 130. The system 10 may include a sourceof negative pressure such as a pump or negative pressure unit 150capable of supplying negative pressure. The pump may comprise a canisteror other container for the storage of wound exudates and other fluidsthat may be removed from the wound. A canister or container may also beprovided separate from the pump. In some embodiments, such asillustrated in FIGS. 1A-1B, the pump 150 can be a canisterless pump suchas the PICO™ pump, as sold by Smith & Nephew. The pump 150 may beconnected to the coupling 160 via a tube 190, or the pump 150 may beconnected directly to the coupling 160 or directly to the bridge 120. Inuse, the dressing 100 is placed over a suitably-prepared wound, whichmay in some cases be filled with a wound packing material such as foamor gauze. The applicator 180 of the fluidic connector 110 has a sealingsurface that is placed over an aperture in the dressing 100 and issealed to the top surface of the dressing 100. Either before, during, orafter connection of the fluidic connector 110 to the dressing 100, thepump 150 is connected via the tube 190 to the coupling 160, or isconnected directly to the coupling 160 or to the bridge 120. The pump isthen activated, thereby supplying negative pressure to the wound.Application of negative pressure may be applied until a desired level ofhealing of the wound is achieved.

With reference initially to FIGS. 2A-B, treatment of a wound withnegative pressure in certain embodiments of the application uses a wounddressing 100 capable of absorbing and storing wound exudate inconjunction with a flexible fluidic connector 110. In some embodiments,the wound dressing 100 may be substantially similar to wound dressingsand have the same or similar components as those described throughoutInternational Patent Publication WO2013175306, WO2014020440,WO2014020443 and U.S. Publication No. 2011/0282309 A1, which areincorporated by reference in their entireties. In other embodiments (notshown), the wound dressing may simply comprise one or more backinglayers configured to form a sealed chamber over the wound site. In someembodiments, it may be preferable for the wound site to be filledpartially or completely with a wound packing material. This woundpacking material is optional, but may be desirable in certain wounds,for example deeper wounds. The wound packing material can be used inaddition to the wound dressing 100. The wound packing material generallymay comprise a porous and conformable material, for example foam(including reticulated foams), and gauze. Preferably, the wound packingmaterial is sized or shaped to fit within the wound site so as to fillany empty spaces. The wound dressing 100 may then be placed over thewound site and wound packing material overlying the wound site. When awound packing material is used, once the wound dressing 100 is sealedover the wound site, negative pressure may be transmitted from a pump orother source of negative pressure through a flexible tubing via thefluidic connector 110 to the wound dressing 100, through the woundpacking material, and finally to the wound site. This negative pressuredraws wound exudate and other fluids or secretions away from the woundsite.

As shown in FIG. 2A, the fluidic connector 110 preferably comprises anenlarged distal end, or head 140 that is in fluidic communication withthe dressing 100 as will be described in further detail below. In oneembodiment, the enlarged distal end has a round or circular shape. Thehead 140 is illustrated here as being positioned near an edge of thedressing 100, but may also be positioned at any location on thedressing. For example, some embodiments may provide for a centrally oroff-centered location not on or near an edge or corner of the dressing100. In some embodiments, the dressing 10 may comprise two or morefluidic connectors 110, each comprising one or more heads 140, influidic communication therewith. In a preferred embodiment, the head 140may measure 30 mm along its widest edge. The head 140 forms at least inpart the applicator 180, described above, that is configured to sealagainst a top surface of the wound dressing.

FIG. 2B illustrates a cross-section through a wound dressing 100 similarto the wound dressing 10 as shown in FIG. 1B and described inInternational Patent Publication WO2013175306, which is incorporated byreference in its entirety, along with fluidic connector 110. The wounddressing 100, which can alternatively be any wound dressing embodimentdisclosed herein or any combination of features of any number of wounddressing embodiments disclosed herein, can be located over a wound siteto be treated. The dressing 100 may be placed to as to form a sealedcavity over the wound site. In a preferred embodiment, the dressing 100comprises a top or cover layer, or backing layer 220 attached to anoptional wound contact layer 222, both of which are described in greaterdetail below. These two layers 220, 222 are preferably joined or sealedtogether so as to define an interior space or chamber. This interiorspace or chamber may comprise additional structures that may be adaptedto distribute or transmit negative pressure, store wound exudate andother fluids removed from the wound, and other functions which will beexplained in greater detail below. Examples of such structures,described below, include a transmission layer 226 and an absorbent layer221.

As illustrated in FIG. 2B, the wound contact layer 222 can be apolyurethane layer or polyethylene layer or other flexible layer whichis perforated, for example via a hot pin process, laser ablationprocess, ultrasound process or in some other way or otherwise madepermeable to liquid and gas. The wound contact layer 222 has a lowersurface 224 and an upper surface 223. The perforations 225 preferablycomprise through holes in the wound contact layer 222 which enable fluidto flow through the layer 222. The wound contact layer 222 helps preventtissue ingrowth into the other material of the wound dressing.Preferably, the perforations are small enough to meet this requirementwhile still allowing fluid to flow therethrough. For example,perforations formed as slits or holes having a size ranging from 0.025mm to 1.2 mm are considered small enough to help prevent tissue ingrowthinto the wound dressing while allowing wound exudate to flow into thedressing. In some configurations, the wound contact layer 222 may helpmaintain the integrity of the entire dressing 100 while also creating anair tight seal around the absorbent pad in order to maintain negativepressure at the wound.

Some embodiments of the wound contact layer 222 may also act as acarrier for an optional lower and upper adhesive layer (not shown). Forexample, a lower pressure sensitive adhesive may be provided on thelower surface 224 of the wound dressing 100 whilst an upper pressuresensitive adhesive layer may be provided on the upper surface 223 of thewound contact layer. The pressure sensitive adhesive, which may be asilicone, hot melt, hydrocolloid or acrylic based adhesive or other suchadhesives, may be formed on both sides or optionally on a selected oneor none of the sides of the wound contact layer. When a lower pressuresensitive adhesive layer is utilized, it may be helpful to adhere thewound dressing 100 to the skin around a wound site. In some embodiments,the wound contact layer may comprise perforated polyurethane film. Thelower surface of the film may be provided with a silicone pressuresensitive adhesive and the upper surface may be provided with an acrylicpressure sensitive adhesive, which may help the dressing maintain itsintegrity. In some embodiments, a polyurethane film layer may beprovided with an adhesive layer on both its upper surface and lowersurface, and all three layers may be perforated together.

A layer 226 of porous material can be located above the wound contactlayer 222. This porous layer, or transmission layer, 226 allowstransmission of fluid including liquid and gas away from a wound siteinto upper layers of the wound dressing. In particular, the transmissionlayer 226 preferably ensures that an open air channel can be maintainedto communicate negative pressure over the wound area even when theabsorbent layer has absorbed substantial amounts of exudates. The layer226 should preferably remain open under the typical pressures that willbe applied during negative pressure wound therapy as described above, sothat the whole wound site sees an equalized negative pressure. The layer226 may be formed of a material having a three dimensional structure.For example, a knitted or woven spacer fabric (for example Baltex 7970weft knitted polyester) or a non-woven fabric could be used.

In some embodiments, the transmission layer 226 comprises a 3D polyesterspacer fabric layer including a top layer (that is to say, a layerdistal from the wound-bed in use) which is a 84/144 textured polyester,and a bottom layer (that is to say, a layer which lies proximate to thewound bed in use) which is a 10 denier flat polyester and a third layerformed sandwiched between these two layers which is a region defined bya knitted polyester viscose, cellulose or the like mono filament fiber.Other materials and other linear mass densities of fiber could of coursebe used.

Whilst reference is made throughout this disclosure to a monofilamentfiber it will be appreciated that a multistrand alternative could ofcourse be utilized. The top spacer fabric thus has more filaments in ayarn used to form it than the number of filaments making up the yarnused to form the bottom spacer fabric layer.

This differential between filament counts in the spaced apart layershelps control moisture flow across the transmission layer. Particularly,by having a filament count greater in the top layer, that is to say, thetop layer is made from a yarn having more filaments than the yarn usedin the bottom layer, liquid tends to be wicked along the top layer morethan the bottom layer. In use, this differential tends to draw liquidaway from the wound bed and into a central region of the dressing wherethe absorbent layer 221 helps lock the liquid away or itself wicks theliquid onwards towards the cover layer where it can be transpired.

Preferably, to improve the liquid flow across the transmission layer 226(that is to say perpendicular to the channel region formed between thetop and bottom spacer layers, the 3D fabric may be treated with a drycleaning agent (such as, but not limited to, Perchloro Ethylene) to helpremove any manufacturing products such as mineral oils, fats and/orwaxes used previously which might interfere with the hydrophiliccapabilities of the transmission layer. In some embodiments, anadditional manufacturing step can subsequently be carried in which the3D spacer fabric is washed in a hydrophilic agent (such as, but notlimited to, Feran Ice 30 g/l available from the Rudolph Group). Thisprocess step helps ensure that the surface tension on the materials isso low that liquid such as water can enter the fabric as soon as itcontacts the 3D knit fabric. This also aids in controlling the flow ofthe liquid insult component of any exudates.

A layer 221 of absorbent material is provided above the transmissionlayer 226. The absorbent material, which comprise a foam or non-wovennatural or synthetic material, and which may optionally comprise asuper-absorbent material, forms a reservoir for fluid, particularlyliquid, removed from the wound site. In some embodiments, the layer 10may also aid in drawing fluids towards the backing layer 220.

The material of the absorbent layer 221 may also prevent liquidcollected in the wound dressing 100 from flowing freely within thedressing, and preferably acts so as to contain any liquid collectedwithin the dressing. The absorbent layer 221 also helps distribute fluidthroughout the layer via a wicking action so that fluid is drawn fromthe wound site and stored throughout the absorbent layer. This helpsprevent agglomeration in areas of the absorbent layer. The capacity ofthe absorbent material must be sufficient to manage the exudates flowrate of a wound when negative pressure is applied. Since in use theabsorbent layer experiences negative pressures the material of theabsorbent layer is chosen to absorb liquid under such circumstances. Anumber of materials exist that are able to absorb liquid when undernegative pressure, for example superabsorber material. The absorbentlayer 221 may typically be manufactured from ALLEVYN™ foam, Freudenberg114-224-4 and/or Chem-Posite™ 11C-450. In some embodiments, theabsorbent layer 221 may comprise a composite comprising superabsorbentpowder, fibrous material such as cellulose, and bonding fibers. In apreferred embodiment, the composite is an airlaid, thermally-bondedcomposite.

In some embodiments, the absorbent layer 221 is a layer of non-wovencellulose fibers having super-absorbent material in the form of dryparticles dispersed throughout. Use of the cellulose fibers introducesfast wicking elements which help quickly and evenly distribute liquidtaken up by the dressing. The juxtaposition of multiple strand-likefibers leads to strong capillary action in the fibrous pad which helpsdistribute liquid. In this way, the super-absorbent material isefficiently supplied with liquid. The wicking action also assists inbringing liquid into contact with the upper cover layer to aid increasetranspiration rates of the dressing.

An aperture, hole, or orifice 227 is preferably provided in the backinglayer 220 to allow a negative pressure to be applied to the dressing100. The fluidic connector 110 is preferably attached or sealed to thetop of the backing layer 220 over the orifice 227 made into the dressing100, and communicates negative pressure through the orifice 227. Alength of tubing may be coupled at a first end to the fluidic connector110 and at a second end to a pump unit (not shown) to allow fluids to bepumped out of the dressing. Where the fluidic connector is adhered tothe top layer of the wound dressing, a length of tubing may be coupledat a first end of the fluidic connector such that the tubing, orconduit, extends away from the fluidic connector parallel orsubstantially to the top surface of the dressing. The fluidic connector110 may be adhered and sealed to the backing layer 220 using an adhesivesuch as an acrylic, cyanoacrylate, epoxy, UV curable or hot meltadhesive. The fluidic connector 110 may be formed from a soft polymer,for example a polyethylene, a polyvinyl chloride, a silicone orpolyurethane having a hardness of 30 to 90 on the Shore A scale. In someembodiments, the fluidic connector 110 may be made from a soft orconformable material.

Preferably the absorbent layer 221 includes at least one through hole228 located so as to underlie the fluidic connector 110. The throughhole 228 may in some embodiments be the same size as the opening 227 inthe backing layer, or may be bigger or smaller. As illustrated in FIG.2B a single through hole can be used to produce an opening underlyingthe fluidic connector 110. It will be appreciated that multiple openingscould alternatively be utilized. Additionally should more than one portbe utilized according to certain embodiments of the present disclosureone or multiple openings may be made in the absorbent layer and theobscuring layer in registration with each respective fluidic connector.Although not essential to certain embodiments of the present disclosurethe use of through holes in the super-absorbent layer may provide afluid flow pathway which remains unblocked in particular when theabsorbent layer is near saturation.

The aperture or through-hole 228 is preferably provided in the absorbentlayer 221 beneath the orifice 227 such that the orifice is connecteddirectly to the transmission layer 226. This allows the negativepressure applied to the fluidic connector 110 to be communicated to thetransmission layer 226 without passing through the absorbent layer 221.This ensures that the negative pressure applied to the wound site is notinhibited by the absorbent layer as it absorbs wound exudates. In otherembodiments, no aperture may be provided in the absorbent layer 221, oralternatively a plurality of apertures underlying the orifice 227 may beprovided. In further alternative embodiments, additional layers such asanother transmission layer or an obscuring layer such as described inInternational Patent Publication WO2014020440 may be provided over theabsorbent layer 221 and beneath the backing layer 220.

The backing layer 220 is preferably gas impermeable, but moisture vaporpermeable, and can extend across the width of the wound dressing 100.The backing layer 220, which may for example be a polyurethane film (forexample, Elastollan SP9109) having a pressure sensitive adhesive on oneside, is impermeable to gas and this layer thus operates to cover thewound and to seal a wound cavity over which the wound dressing isplaced. In this way an effective chamber is made between the backinglayer 220 and a wound site where a negative pressure can be established.The backing layer 220 is preferably sealed to the wound contact layer222 in a border region around the circumference of the dressing,ensuring that no air is drawn in through the border area, for examplevia adhesive or welding techniques. The backing layer 220 protects thewound from external bacterial contamination (bacterial barrier) andallows liquid from wound exudates to be transferred through the layerand evaporated from the film outer surface. The backing layer 220preferably comprises two layers; a polyurethane film and an adhesivepattern spread onto the film. The polyurethane film is preferablymoisture vapor permeable and may be manufactured from a material thathas an increased water transmission rate when wet. In some embodimentsthe moisture vapor permeability of the backing layer increases when thebacking layer becomes wet. The moisture vapor permeability of the wetbacking layer may be up to about ten times more than the moisture vaporpermeability of the dry backing layer.

The absorbent layer 221 may be of a greater area than the transmissionlayer 226, such that the absorbent layer overlaps the edges of thetransmission layer 226, thereby ensuring that the transmission layerdoes not contact the backing layer 220. This provides an outer channelof the absorbent layer 221 that is in direct contact with the woundcontact layer 222, which aids more rapid absorption of exudates to theabsorbent layer. Furthermore, this outer channel ensures that no liquidis able to pool around the circumference of the wound cavity, which mayotherwise seep through the seal around the perimeter of the dressingleading to the formation of leaks. As illustrated in FIGS. 2A-2B, theabsorbent layer 221 may define a smaller perimeter than that of thebacking layer 220, such that a boundary or border region is definedbetween the edge of the absorbent layer 221 and the edge of the backinglayer 220.

As shown in FIG. 2B, one embodiment of the wound dressing 100 comprisesan aperture 228 in the absorbent layer 221 situated underneath thefluidic connector 110. In use, for example when negative pressure isapplied to the dressing 100, a wound facing portion of the fluidicconnector may thus come into contact with the transmission layer 226,which can thus aid in transmitting negative pressure to the wound siteeven when the absorbent layer 221 is filled with wound fluids. Someembodiments may have the backing layer 220 be at least partly adhered tothe transmission layer 226. In some embodiments, the aperture 228 is atleast 1-2 mm larger than the diameter of the wound facing portion of thefluidic connector 11, or the orifice 227.

In particular for embodiments with a single fluidic connector 110 andthrough hole, it may be preferable for the fluidic connector 110 andthrough hole to be located in an off-center position as illustrated inFIG. 2A. Such a location may permit the dressing 100 to be positionedonto a patient such that the fluidic connector 110 is raised in relationto the remainder of the dressing 100. So positioned, the fluidicconnector 110 and the filter 214 may be less likely to come into contactwith wound fluids that could prematurely occlude the filter 214 so as toimpair the transmission of negative pressure to the wound site.

Turning now to the fluidic connector 110, preferred embodiments comprisea sealing surface 216, a bridge 211 (corresponding to bridge 120 inFIGS. 1A-1B) with a proximal end 130 and a distal end 140, and a filter214. The sealing surface 216 preferably forms the applicator previouslydescribed that is sealed to the top surface of the wound dressing. Insome embodiments a bottom layer of the fluidic connector 110 maycomprise the sealing surface 216, such as layer 540 in FIG. 5C below.The fluidic connector 110 may further comprise an upper surfacevertically spaced from the sealing surface 216, which in someembodiments is defined by a separate upper layer of the fluidicconnector such as layer 510 in FIG. 5C below. In other embodiments theupper surface and the lower surface may be formed from the same piece ofmaterial. In some embodiments the sealing surface 216 may comprise atleast one aperture 229 therein to communicate with the wound dressing.In some embodiments the filter 214 may be positioned across the opening229 in the sealing surface, and may span the entire opening 229. Thesealing surface 216 may be configured for sealing the fluidic connectorto the cover layer of the wound dressing, and may comprise an adhesiveor weld. In some embodiments, the sealing surface 216 may be placed overan orifice in the cover layer with optional spacer elements 215configured to create a gap between the filter 214 and the transmissionlayer 226. In other embodiments, the sealing surface 216 may bepositioned over an orifice in the cover layer and an aperture in theabsorbent layer 221, permitting the fluidic connector 110 to provide airflow through the transmission layer 226. In some embodiments, the bridge211 may comprise a first fluid passage 212 in communication with asource of negative pressure, the first fluid passage 212 comprising aporous material, such as a 3D knitted material, which may be the same ordifferent than the porous layer 226 described previously. The bridge 211is preferably encapsulated by at least one flexible film layer 208, 210having a proximal and distal end and configured to surround the firstfluid passage 212, the distal end of the flexible film being connectedthe sealing surface 216. The filter 214 is configured to substantiallyprevent wound exudate from entering the bridge, and spacer elements 215are configured to prevent the fluidic connector from contacting thetransmission layer 226. These elements will be described in greaterdetail below.

Preferably, the fluid passage 212 is constructed from a compliantmaterial that is flexible and that also permits fluid to pass through itif the spacer is kinked or folded over. Suitable materials for the fluidpassage 212 include without limitation foams, including open-cell foamssuch as polyethylene or polyurethane foam, meshes, 3D knitted fabrics,non-woven materials, and fluid channels. In some embodiments, the fluidpassage 212 may be constructed from materials similar to those describedabove in relation to the transmission layer 226. Advantageously, suchmaterials used in the fluid passage 212 not only permit greater patientcomfort, but may also provide greater kink resistance, such that thefluid passage 212 is still able to transfer fluid from the wound towardthe source of negative pressure while being kinked or bent.

In some embodiments, the fluid passage 212 may be comprised of a wickingfabric, for example a knitted or woven spacer fabric (such as a knittedpolyester 3D fabric, Baltex 7970®, or Gehring 879®) or a nonwovenfabric. These materials selected are preferably suited to channelingwound exudate away from the wound and for transmitting negative pressureand/or vented air to the wound site, and may also confer a degree ofkinking or occlusion resistance to the fluid passage 212. In someembodiments, the wicking fabric may have a three-dimensional structure,which in some cases may aid in wicking fluid or transmitting negativepressure. In certain embodiments, including wicking fabrics, thesematerials remain open and capable of communicating negative pressure toa wound area under the typical pressures used in negative pressuretherapy, for example between 40 to 150 mmHg. In some embodiments, thewicking fabric may comprise several layers of material stacked orlayered over each other, which may in some cases be useful in preventingthe fluid passage 212 from collapsing under the application of negativepressure. In other embodiments, the wicking fabric used in the fluidpassage 212 may be between 1.5 mm and 6 mm; more preferably, the wickingfabric may be between 3 mm and 6 mm thick, and may be comprised ofeither one or several individual layers of wicking fabric. In otherembodiments, the fluid passage 212 may be between 1.2-3 mm thick, andpreferably thicker than 1.5 mm Some embodiments, for example a suctionadapter used with a dressing which retains liquid such as wound exudate,may employ hydrophobic layers in the fluid passage 212, and only gasesmay travel through the fluid passage 212. Additionally, and as describedpreviously, the materials used in the system are preferably conformableand soft, which may help to avoid pressure ulcers and othercomplications which may result from a wound treatment system beingpressed against the skin of a patient.

Preferably, the filter element 214 is impermeable to liquids, butpermeable to gases, and is provided to act as a liquid bather and toensure that no liquids are able to escape from the wound dressing 100.The filter element 214 may also function as a bacterial barrier.Typically the pore size is 0.2 μm. Suitable materials for the filtermaterial of the filter element 214 include 0.2 micron Gore™ expandedPTFE from the MMT range, PALL Versapore™ 200R, and Donaldson™ TX6628.Larger pore sizes can also be used but these may require a secondaryfilter layer to ensure full bioburden containment. As wound fluidcontains lipids it is preferable, though not essential, to use anoleophobic filter membrane for example 1.0 micron MMT-332 prior to 0.2micron MMT-323. This prevents the lipids from blocking the hydrophobicfilter. The filter element can be attached or sealed to the port and/orthe cover film over the orifice. For example, the filter element 214 maybe molded into the fluidic connector 110, or may be adhered to one orboth of the top of the cover layer and bottom of the suction adapter 110using an adhesive such as, but not limited to, a UV cured adhesive.

It will be understood that other types of material could be used for thefilter element 214. More generally a microporous membrane can be usedwhich is a thin, flat sheet of polymeric material, this containsbillions of microscopic pores. Depending upon the membrane chosen thesepores can range in size from 0.01 to more than 10 micrometers.Microporous membranes are available in both hydrophilic (waterfiltering) and hydrophobic (water repellent) forms. In some embodimentsof the invention, filter element 214 comprises a support layer and anacrylic co-polymer membrane formed on the support layer. Preferably thewound dressing 100 according to certain embodiments of the presentinvention uses microporous hydrophobic membranes (MHMs). Numerouspolymers may be employed to form MHMs. For example, the MHMs may beformed from one or more of PTFE, polypropylene, PVDF and acryliccopolymer. All of these optional polymers can be treated in order toobtain specific surface characteristics that can be both hydrophobic andoleophobic. As such these will repel liquids with low surface tensionssuch as multi-vitamin infusions, lipids, surfactants, oils and organicsolvents.

MHMs block liquids whilst allowing air to flow through the membranes.They are also highly efficient air filters eliminating potentiallyinfectious aerosols and particles. A single piece of MHM is well knownas an option to replace mechanical valves or vents. Incorporation ofMHMs can thus reduce product assembly costs improving profits andcosts/benefit ratio to a patient.

The filter element 214 may also include an odor absorbent material, forexample activated charcoal, carbon fiber cloth or Vitec Carbotec-RTQ2003073 foam, or the like. For example, an odor absorbent material mayform a layer of the filter element 214 or may be sandwiched betweenmicroporous hydrophobic membranes within the filter element. The filterelement 214 thus enables gas to be exhausted through the orifice.Liquid, particulates and pathogens however are contained in thedressing.

The wound dressing 100 may comprise spacer elements 215 in conjunctionwith the fluidic connector 110 and the filter 214. With the addition ofsuch spacer elements 215 the fluidic connector 110 and filter 214 may besupported out of direct contact with the absorbent layer 220 and/or thetransmission layer 226. The absorbent layer 220 may also act as anadditional spacer element to keep the filter 214 from contacting thetransmission layer 226. Accordingly, with such a configuration contactof the filter 214 with the transmission layer 226 and wound fluidsduring use may thus be minimized.

In particular for embodiments with a single fluidic connector 110 andthrough hole, it may be preferable for the fluidic connector 110 andthrough hole to be located in an off-center position as illustrated inFIGS. 2A-B. Such a location may permit the dressing 100 to be positionedonto a patient such that the fluidic connector 110 is raised in relationto the remainder of the dressing 100. So positioned, the fluidicconnector 110 and the filter 214 may be less likely to come into contactwith wound fluids that could prematurely occlude the filter 214 so as toimpair the transmission of negative pressure to the wound site.

FIGS. 3A-C illustrate various embodiments of the head 140 of the fluidicconnector 110. Preferably, the fluidic connector 110 illustrated in FIG.2A is enlarged at the distal end to be placed over an orifice in thecover layer and the aperture in the absorbent layer of a wound dressing,for example wound dressing 100 of FIGS. 2A-B, and may form a “teardrop”or other enlarged shape. FIG. 3A illustrates a fluidic connector 110with a substantially triangular head 140. FIG. 3B illustrates a fluidicconnector 110 with a substantially pentagonal head 140. FIG. 3Aillustrates a fluidic connector 110 with a substantially circular head140.

FIGS. 4A-D illustrate the use of an embodiment of a negative pressuretherapy wound treatment system being used to treat a wound site on apatient. FIG. 4A shows a wound site 400 being cleaned and prepared fortreatment. Here, the healthy skin surrounding the wound site 400 ispreferably cleaned and excess hair removed or shaved. The wound site 400may also be irrigated with sterile saline solution if necessary.Optionally, a skin protectant may be applied to the skin surrounding thewound site 400. If necessary, a wound packing material, such as foam orgauze, may be placed in the wound site 400. This may be preferable ifthe wound site 400 is a deeper wound.

After the skin surrounding the wound site 400 is dry, and with referencenow to FIG. 4B, the wound dressing 100 may be positioned and placed overthe wound site 400. Preferably, the wound dressing 100 is placed withthe wound contact layer over and/or in contact with the wound site 400.In some embodiments, an adhesive layer is provided on the lower surfaceof the wound contact layer, which may in some cases be protected by anoptional release layer to be removed prior to placement of the wounddressing 100 over the wound site 400. Preferably, the dressing 100 ispositioned such that the fluidic connector 110 is in a raised positionwith respect to the remainder of the dressing 10 so as to avoid fluidpooling around the port. In some embodiments, the dressing 100 ispositioned so that the fluidic connector 110 is not directly overlyingthe wound, and is level with or at a higher point than the wound. Tohelp ensure adequate sealing for TNP, the edges of the dressing 100 arepreferably smoothed over to avoid creases or folds.

With reference now to FIG. 4C, the dressing 10 is connected to the pump150. The pump 150 is configured to apply negative pressure to the woundsite via the dressing 100, and typically through a conduit. In someembodiments, and as described herein, a fluidic connector 110 may beused to join the conduit 190 from the pump to the dressing 100. Wherethe fluidic connector is adhered to the top layer of the wound dressing,a length of tubing may be coupled at a first end of the fluidicconnector such that the tubing, or conduit, extends away from thefluidic connector parallel to the top of the dressing. In someembodiments the conduit may comprise a fluidic connector. It isexpressly contemplated that a conduit may be a soft bridge, a hard tube,or any other apparatus which may serve to transport fluid. Upon theapplication of negative pressure with the pump 150, the dressing 100 mayin some embodiments partially collapse and present a wrinkled appearanceas a result of the evacuation of some or all of the air underneath thedressing 100. In some embodiments, the pump 150 may be configured todetect if any leaks are present in the dressing 100, such as at theinterface between the dressing 100 and the skin surrounding the woundsite 400. Should a leak be found, such leak is preferably remedied priorto continuing treatment.

Turning to FIG. 4D, additional fixation strips 410 may also be attachedaround the edges of the dressing 100. Such fixation strips 410 may beadvantageous in some situations so as to provide additional sealingagainst the skin of the patient surrounding the wound site 400. Forexample, the fixation strips 410 may provide additional sealing for whena patient is more mobile. In some cases, the fixation strips 410 may beused prior to activation of the pump 150, particularly if the dressing100 is placed over a difficult to reach or contoured area.

Treatment of the wound site 400 preferably continues until the wound hasreached a desired level of healing. In some embodiments, it may bedesirable to replace the dressing 100 after a certain time period haselapsed, or if the dressing is full of wound fluids. During suchchanges, the pump 150 may be kept, with just the dressing 100 beingchanged.

Further details of dressings and other apparatuses that may be used withthe, fluidic connectors described herein include, but are not limitedto, dressings described in International Patent Publication WO2012020440 and WO2014020443, the entireties of which are herebyincorporated by reference.

FIGS. 5A-B illustrate an embodiment of a flexible port or fluidicconnector 500. FIG. 5C illustrates a perspective exploded view thefluidic connector 500 that may be used to connect a wound dressing to asource of negative pressure. The fluidic connector 500 comprises a toplayer 510, a spacer layer 520, a filter element 530, a bottom layer 540,and a conduit 550. The conduit optionally comprises a coupling 560. Insome embodiments the conduit may comprise a fluidic connector. It isexpressly contemplated that a conduit may be a soft bridge, a hard tube,or any other apparatus which may serve to transport fluid. The distalend of the fluidic connector 500 (the end connectable to a dressing) isdepicted as having an enlarged circular shape, although it will beappreciated that any suitable shape may be used and that the distal endneed not be enlarged. For example, the distal end can have any of theshapes shown in FIGS. 3A-3C above.

The bottom layer 540 may comprise an elongate bridge portion 544, anenlarged (e.g., rounded or circular) sealing portion 545, and an orifice541. In some embodiments a plurality of orifices may be provided in thebottom layer. Some embodiments of the rounded sealing portion 545 maycomprise a layer of adhesive, for example a pressure sensitive adhesive,on the lower surface for use in sealing the fluidic connector 500 to adressing. For example, the fluidic connector may be sealed to a coverlayer of the dressing. The orifice 541 in the bottom layer 540 of theport 500 may be aligned with an orifice in the cover layer of thedressing in order to transmit negative pressure through the dressing andinto a wound site.

The top layer 515 may be substantially the same shape as the bottomlayer in that it comprises an elongate bridge 514 and an enlarged (e.g.,rounded or circular) portion 545. The top layer 515 and the bottom layer545 may be sealed together, for example by heat welding. In someembodiments, the bottom layer 545 may be substantially flat and the toplayer 515 may be slightly larger than the bottom layer 545 in order toaccommodate the height of the spacer layer 520 and seal to the bottomlayer 545. In other embodiments, the top layer 515 and bottom layer 3145may be substantially the same size, and the layers may be sealedtogether approximately at the middle of the height of the spacer layer520. In some embodiments, the elongate bridge portions 544, 514 may havea length of 10 cm (or about 10 cm) or more, more preferably a length of20 cm (or about 20 cm) or more and in some embodiments, may be about 69cm (or 27 cm) long. Some embodiments of the entire fluidic connector,from a proximal-most edge of the top and bottom layers to a distal-mostedge of the top and bottom layers, may be between 20 cm and 80 cm (orabout 20 cm to about 80 cm) long, more preferably about 60 cm and 80 cm(or between about 60 cm and about 80 cm) long, for example about 70 cmlong. In some embodiments, the elongate bridge portions may have a widthof between 1 cm and 4 cm (or between about 1 cm and about 4 cm), and inone embodiment, is about 2.5 cm wide. The ratio of the length of theelongate bridge portions 544, 514 to their widths may in someembodiments exceed 6:1, and may more preferably exceed 8:1 or even 10:1.The diameter of the circular portion 545, 515 may be about 3.5 cm insome embodiments.

The bottom and top layers may comprise at least one layer of a flexiblefilm, and in some embodiments may be transparent. Some embodiments ofthe bottom layer 540 and top layer 515 may be polyurethane, and may beliquid impermeable.

The fluidic connector 500 may comprise a spacer layer 520, such as the3D fabric discussed above, positioned between the lower layer 540 andthe top layer 510. The spacer layer 520 may be made of any suitablematerial, for example material resistant to collapsing in at least onedirection, thereby enabling effective transmission of negative pressuretherethrough. Instead of or in addition to the 3D fabric discussedabove, some embodiments of the spacer layer 520 may comprise a fabricconfigured for lateral wicking of fluid, which may comprise viscose,polyester, polypropylene, cellulose, or a combination of some or all ofthese, and the material may be needle-punched. Some embodiments of thespacer layer 520 may comprise polyethylene in the range of 40-160 gramsper square meter (gsm) (or about 40 to about 160 gsm), for example 80(or about 80) gsm. Such materials may be constructed so as to resistcompression under the levels of negative pressure commonly appliedduring negative pressure therapy.

The spacer layer 520 may comprise an elongate bridge portion 524, anenlarged (e.g., rounded or circular) portion 525, and may optionallyinclude a fold 521. In some embodiments, the elongate bridge portion mayhave dimensions in the same ranges as the bridge portions of the upperand lower layers described above though slightly smaller, and in oneembodiment is about 25.5 cm long and 1.5 cm wide. Similarly, thediameter of the circular portion 525 may be slightly smaller than thediameters of the enlarged ends 545, 515, and in one embodiment is about2 cm. Some embodiments of the spacer layer 520 may have adhesive on oneor both of its proximal and distal ends (e.g., one or more dabs ofadhesive) in order to secure the spacer layer 520 to the top layer 510and/or the bottom layer 540. Adhesive may also be provided along aportion or the entire length of the spacer layer. In other embodiments,the spacer layer 520 may be freely movable within the sealed chamber ofthe top and bottom layers.

The fold 521 of the spacer layer may make the end of the fluidicconnector 500 softer and therefore more comfortable for a patient, andmay also help prevent the conduit 550 from blockage. The fold 521 mayfurther protect the end of the conduit 550 from being occluded by thetop or bottom layers. The fold 521 may, in some embodiments, be between1 cm and 3 cm (or between about 1 cm and about 3 cm) long, and in oneembodiment is 2 cm (or about 2 cm) long. The spacer layer may be foldedunderneath itself that is toward the bottom layer 540, and in otherembodiments may be folded upward toward the top layer 510. Otherembodiments of the spacer layer 520 may contain no fold. A slot orchannel 522 may extend perpendicularly away from the proximal end of thefold 521, and the conduit 550 may rest in the slot or channel 522. Insome embodiments the slot 522 may extend through one layer of the fold,and in others it may extend through both layers of the fold. The slot522 may, in some embodiments, be 1 cm (or about 1 cm) long. Someembodiments may instead employ a circular or elliptical hole in the fold521. The hole may face proximally so that the conduit 550 may beinserted into the hole and rest between the folded layers of spacerfabric. In some embodiments, the conduit 550 may be adhered to thematerial of the fold 521, while in other embodiments it may not.

The fluidic connector 500 may have a filter element 530 located adjacentthe orifice 541, and as illustrated is located between the lower layer540 and the spacer layer 520. The filter element 530 may be positionedacross the opening or orifice of the fluidic connector 500. The filterelement 530 is impermeable to liquids, but permeable to gases. Thefilter element may be similar to the element described above withrespect to FIG. 1B, and as illustrated may have a round or disc shape.The filter element 530 can act as a liquid bather, to substantiallyprevent or inhibit liquids from escaping from the wound dressing, aswell as an odor bather. The filter element 530 may also function as abacterial bather. In some embodiments, the pore size of the filterelement 530 can be approximately 0.2 μm. Suitable materials for thefilter material of the filter element include 0.2 micron Gore™ expandedPTFE from the MMT range, PALL Versapore™ 200R, and Donaldson™ TX6628.The filter element 530 thus enables gas to be exhausted through theorifice. Liquid, particulates and pathogens however are contained in thedressing. Larger pore sizes can also be used but these may require asecondary filter layer to ensure full bioburden containment. As woundfluid contains lipids it is preferable, though not essential, to use anoleophobic filter membrane for example 1.0 micron MMT-332 prior to 0.2micron MMT-323. This prevents the lipids from blocking the hydrophobicfilter. In some embodiments, the filter element 530 may be adhered toone or both of top surface of the bottom layer 540 and the bottomsurface of the spacer layer 520 using an adhesive such as, but notlimited to, a UV cured adhesive. In other embodiments, the filter 530may be welded to the inside of the spacer layer 520 and to the topsurface of the bottom layer 540. The filter may also be providedadjacent the orifice on a lower surface of the bottom layer 540. Otherpossible details regarding the filter are disclosed in U.S. Patent Pub.No. 2011/0282309 and incorporated by reference herein.

The proximal end of the fluidic connector 500 may be connected to thedistal end of a conduit 550. The conduit 550 may comprise one or morecircular ribs 551. The ribs 551 may be formed in the conduit 550 bygrooves in a mold during the manufacturing of the conduit. During heatwelding of the upper and lower layers 515, 545 melted material fromthose layers may flow around the ribs 551, advantageously providing astronger connection between the conduit 550 and the layers. As a result,it may be more difficult to dislodge the conduit 550 out from betweenthe layers during use of the fluidic connector 500.

The proximal end of the conduit 550 may be optionally attached to acoupling 560. The coupling 560 may be used to connect the fluidicconnector 500 to a source of negative pressure, or in some embodimentsto an extension conduit which may in turn be connected to a source ofnegative pressure. As explained in more detail below with respect toFIGS. 8A and 8B, the proximal end of the conduit 550, which is insertedinto the spacer fabric 520, may be shaped in such a way to reduce thepossibility of occlusion. For example, some embodiments may have atriangular portion cut out of the end of the conduit, and otherembodiments may have a plurality of holes therethrough.

FIG. 6 illustrates an embodiment of a wound dressing 610 with a fluidicconnector 620 such as described above with respect to FIGS. 5A-Cattached to the dressing. The fluidic connector 620 may be the fluidicconnector described above in FIGS. 5A-C. The fluidic connector 620 maycomprise a conduit 630 and a coupling 640 for connecting the fluidicconnector to a source of negative pressure or to an extension conduit.Although in this depiction the fluidic connector 620 is connected over acircular window in the obscuring layer of the dressing 610, in otherembodiments the fluidic connector 620 may be connected over a maltesecross in the obscuring layer. In some embodiments, the maltese cross maybe of a larger diameter than the fluidic connector 620 and may be atleast partially viewable after the fluidic connector 620 is attached tothe dressing 610. Further details regarding the dressing 610 and otherdressings to which the fluidic connector can be connected are describedin International Patent Publications WO2012020440 and WO2014020443, theentireties of which are hereby incorporated by reference. Furtherdetails regarding wound dressings and fluidic connectors can be found inU.S. patent application Ser. No. 14/715,527, titled “FLUIDIC CONNECTORFOR NEGATIVE PRESSURE WOUND THERAPY” filed May 18, 2015, published as US2016/0339158, the entirety of which are hereby incorporated byreference.

A negative pressure wound therapy system may include a three-dimensionalfilter element to prevent or inhibit wound fluid or exudate fromescaping from a wound dressing. In some embodiments, thethree-dimensional filter element may be placed within the wound dressingand/or the fluidic connector, and replace the filter element such as thefilter element 214 described in relation to FIG. 2B, or the filterelement 530 described in relation to FIG. 5C. In some embodiments, anegative pressure wound therapy system may contain both thethree-dimensional filter element and the filter element such as thefilter element 214 described in relation to FIG. 2B or the filterelement 530 described in relation to FIG. 5C.

The three-dimensional filter element may have a substantial thickness orheight perpendicular to a width, a length, and/or a diameter, and thusdefine three-dimensional shape, as compared with the filter elements 214or 530, which are relatively flatter and have minimal thickness orheight. Thus, the three-dimensional filter may have more surface areathan a two-dimensional filter having a same cross-sectional area. Forexample, a cylindrical three-dimensional filter element having across-sectional radius of r and a height of h may have a surface area of2 πrh (side wall)+πr² (bottom surface), while a circular two-dimensionalfilter having a radius r will only have a surface area of πr². Theincreased surface area of the three-dimensional filter may allowimproved filtering capacity and better air flow even when the filter ispartially blocked. Such advantage of three-dimensional filters isfurther depicted in FIGS. 7A-B, wherein a NPWT system 700 having atwo-dimensional filter 710, and another NPWT system 750 having a threedimensional filter 720 are schematically shown. In FIGS. 7A and 7B, theNPWT systems 700 and 750 without negative pressure applied are shown onthe left, while the NPWT systems 700 and 750 under negative pressure areshown on the right. As shown in FIG. 7B, the three-dimensional filterelement 720 may be configured to maintain its height under negativepressure, thereby maintain its increased surface area.

FIG. 8 illustrates a cross-sectional view through an embodiment of anegative pressure wound therapy apparatus having a wound dressing 800along with a fluidic connector 810. Each of the wound dressing 800 andthe fluidic connector 810 may be constructed similar to the wounddressing 100 and the fluidic connecter 110 shown in and described inrelation to FIG. 2B or elsewhere in the specification, respectively,except as noted below. Thus, the references numerals used to designatethe various components of the wound dressing 800 and the fluidicconnector 810 are identical to those used for identifying thecorresponding components of the wound dressing 100 and the fluidicconnector 110.

In some embodiments, such as shown in FIG. 8 , the fluidic connector 810may include a three-dimensional filter element 850. Thethree-dimensional filter element 850 may be positioned across theopening 229 in the sealing surface 216 of the fluidic connector 810, andmay span the entire opening 229 and/or the aperture 227 of the coverlayer 220. In some embodiments, the three-dimensional filter element 850may located within the fluidic connector. In some embodiments, thefilter element 850 may extrude out or extend out of the fluidicconnector 810. The extruded-out portion of the filter element 850 maypass and extend through the aperture 227 of the cover layer 220 and/orthe aperture or through-hole 228 of the absorbent layer 221 of thedressing 800. In some embodiments, the aperture or through-hole 228 maybe a recess which only partially extends through the thickness of theabsorbent layer 221. The aperture, through-hole, and the recess 228 ofthe absorbent layer 221 are interchangeable variations of cut-outs inthe absorbent layer 221, and these terms may be used interchangeablyhereinafter. In some embodiments, the sealing surface 216 may be placedover the orifice 227 in the cover layer with optional spacer elements215 configured to offset the height or thickness of thethree-dimensional filter element 850, such that only pre-determinedportion of the three-dimensional filter 850 extends out of the sealingsurface of the fluidic connector through the opening 229 and maintains agap between the filter element 850 and the transmission layer 226. Insome embodiments, the filter element 850 may be entirely within thefluidic connector 810 and does not extend to the wound dressing 800.

Alternatively, a three-dimensional filter may be placed at/on the wounddressing 800. For example, in some embodiments, the three-dimensionalfilter may be placed within the aperture 227 of the cover layer 220 andthe aperture 228 of the absorbent layer 221. In some embodiments, thethree-dimensional filter may be thinner than the depth of the aperture228, such that the three-dimensional filter is fully embedded in theaperture 228. In some embodiments, the three-dimensional filter may bethicker than the depth of the aperture 228, such that thethree-dimensional filter element extrudes out from the absorbentlayer/wound dressing through the aperture 228. However, thethree-dimensional filter element may be placed at any location relativeto the absorbent layer 221. In some embodiments, the three-dimensionalfilter may be placed above the absorbent layer 221, or next to the sidewall of the absorbent layer 221.

The three-dimensional filter element may be fixed to the fluidicconnector or the wound dressing element by any suitable means, such asglue or an adhesive, as explained below in further detail. In someembodiments, the three-dimensional filter element may be molded with thefluidic connector or the wound dressing as an integrated part.

The filter element 850 may be constructed to conform to the shape andthe size of the opening 229 and/or the aperture in the wound dressing800. In some embodiments, the filter 850 may have the exact same shapeand size with the aperture 228 and/or the opening 229, such that woundexudate does not leak along the gap between the perimeter of thethree-dimensional filter element 850 and the aperture 228 or the opening229. In some embodiments, the three-dimensional filter element haslength or width greater than 1 mm, 3 mm, 5 mm, 1 cm, 3 cm or 5 cm. Also,the three-dimensional filer 850 may be constructed to have a height orthickness such that the gap between the three-dimensional filter and thebottom of the recess 228 or the transmission layer 226 may be maintainedunder negative pressure. For example, the height of thethree-dimensional filter 850 may not be greater than the thickness ofthe absorbent layer 221 under negative pressure, such that thethree-dimensional filter 850 does not reach the transmission layer 226through the aperture 228 even when the absorbent layer 221 collapsesunder negative pressure. However, at the same time, thethree-dimensional filter element may have a certain amount of thicknessor height to have an advantage of having a three-dimensional structuredescribed in this section or elsewhere in the specification. In someembodiments, the three-dimensional filter 850 may have a thicknessgreater than, for example, 1 mm, 2 mm, 3 mm, 5 mm, 1 cm or 5 cm. In someembodiments, the three-dimensional filter 850 may have a thickness orheight greater than its length or width. In some embodiments, thethree-dimensional filter 850 may have a thickness or height smaller thanits length or width.

The three-dimensional filter may have any suitable shape. For example,in some embodiments, the filter element 850 may be cylindrical orcuboid. In some embodiments, the cross-section along the horizontalplane of the filter element 850 may have a circular, elliptical, square,rectangular, diamond, or any other suitable cross-sectional shape.

The three-dimensional filter element may include one or more filterlayers constructed from filter materials forming the three-dimensionalshape. In some embodiments, the three-dimensional filter element alsoincludes an optional spacer to maintain the three-dimensional shape ofthe filter element. FIG. 9 illustrates a vertical cross-sectional viewof an embodiment of a three-dimensional filter element 900 similar tothe three-dimensional filter element 850 described in relation to FIG. 8or any three-dimensional filter elements described in this section orelsewhere in the specification. The three-dimensional filter element 900may include a filter layer 910 and a spacer material core 920. In someembodiments, the filter layer 910 may at least partially enclose aspacer material core 920, such that the filter layer is placed on theoutside of the three-dimensional filter element to maximize filteringarea, while the spacer material core inside allows air flow and supportsthe overall structure of the three-dimensional filter element. Havingthe spacer material core may also contribute to the ease of constructingthe three-dimensional filter element, as it may be easier to apply thefilter layer over the three-dimensional-structured spacer material corethan building a three-dimensional structure solely with the filtermaterial.

Preferably, the filter layer 910 is impermeable to liquids, butpermeable to gases, and may be constructed from any materials suitablefor the filter element 214 described in relation to FIG. 2B or thefilter element 530 described in relation to FIG. 5C. For example, thefilter layer 910 may be constructed from 0.2 micron Gore™ expanded PTFEfrom the MMT range, PALL Versapore™ 200R, PALL Versapore™ 1200R andDonaldson™ TX6628. Larger pore sizes can also be used but these mayrequire a secondary filter layer to ensure full bioburden containment.As wound fluid contains lipids it is preferable, though not essential,to use an oleophobic filter membrane for example 1.0 micron MMT-332prior to 0.2 micron MMT-323. This prevents the lipids from blocking thehydrophobic filter. In some embodiments, the filter material 910 may behydrophobic. A portion of the filter layer can be attached or sealed tothe fluidic connector and/or the wound dressing. For example, the filterlayer 910 may be molded into the fluidic connector, or may be adhered toone or both of the wound dressing and the suction adapter using anadhesive such as, but not limited to, a UV cured adhesive, as describedfurther below in relation to FIGS. 10A-11B. The filter layer 910 of thethree-dimensional filter element 900 may be constructed not to collapsesubstantially under negative pressure, such that it maintains theunobstructed air flow under the negative pressure.

The spacer material core 920 may be constructed from any soft spacermaterial that allows an air flow throughout. For example, in someembodiments, the spacer material core 920 may be constructed frommaterials suitable for the absorbent layer 220 described in relation toFIG. 2B, such as ALLEVYN™ foam, Freudenberg 114-224-4 and/orChem-Posite™ 11C-450, Baltex 7970®, or fibrous material such ascellulose. The filter material 910 may be adhered to the spacer materialcore 910 using an adhesive such as, but not limited to, a UV curedadhesive. The spacer material core 920 may also be constructed from anysoft spacer material that allows an air flow throughout. For example, insome embodiments, the spacer material core 920 may be constructed frommaterials suitable for the spacer layer 520, the spacer element 215, orany other spacers described elsewhere in the specification, such as aknitted polyester 3D fabric, Gehring 879®, a fabric comprising compriseviscose, polyester, polypropylene, cellulose, or a combination of someor all of these.

A negative pressure wound therapy system including the three-dimensionalfilter element may be constructed in various ways. FIGS. 10A-11Billustrates different embodiments of a wound dressing and a fluidicconnector having a three-dimensional filter element.

FIG. 10A illustrates a schematic view of an embodiment of the NPWTsystem 1000 where the three-dimensional filter element 1050 is attachedto the fluidic connector 1020. In some embodiments, the filter element1050 may have a filter layer 1055 with a flap portion 1059, and the flapportion 1059 may adhere to the fluidic connector 1020, for example,using an adhesive 1057.

FIG. 10B illustrates a plan view of an embodiment of the fluidicconnector 1020. The fluidic connector 1020 may be constructed similar tothe fluidic connector 500 shown in and described in relation to FIG. 5Cor elsewhere in the specification, except that the fluidic connector1020 includes the three-dimensional filter element 1050, instead of thefilter element 530. Thus, the references numerals used to designate thevarious components of the fluidic connector 1020 are identical to thoseused for identifying the corresponding components of the fluidicconnector 500.

As shown in FIG. 10B, in some embodiments, the filter element 1050 mayadhere to the fluidic connector 1020 in a similar fashion to the filterelement 530 adhering to the fluidic connector 500 as described inrelation to FIG. 5C. For example, the filter element 1050 may be locatedadjacent the orifice of the fluidic connector orifice 541, and the flapportion 1059 may be located between the lower layer 540 and the spacerlayer 520. The filter element 1050 may be positioned across the openingor orifice 541 of the fluidic connector 1020. In some embodiments, theflap portion 1059 of the filter element 1050 may be adhered to one orboth of the top surface of the bottom layer 540 and the bottom surfaceof the spacer layer 520 using an adhesive such as, but not limited to, aUV cured adhesive. In other embodiments, the flap portion 1059 or theentire filter element 1050 may be welded to the inside of the spacerlayer 520 and to the top surface of the bottom layer 540. The filterelement 1050 may also be provided adjacent the orifice on a lowersurface of the bottom layer 540.

In some embodiments, the filter element 1050 may not include the flapportion 1057, and the mechanism to attach the filter element 1050 to thefluidic connector 1020 may not be limited to the above embodiment. Forexample, the filter element may be adhered or welded to any portion ofthe fluidic connector 1020 using any suitable methods, so as to preventwound fluid and exudate from the wound dressing leaks into the fluidicconnector under negative pressure.

In some embodiments, the filter element 1050 may further include aspacer material core within the space defined by the filter layer 1055as described above in relation to FIG. 9 . To construct suchthree-dimensional filters, in some embodiments, a filter material forthe filter layer 1055 may be cut into a thin strip and looped into atube. Then, a spacer material may be cut into a disc using, for example,a clicker press, to form the spacer material core. Then, the tube of thefilter material may be placed around the disc of the spacer materialcore and held in place with, for example, an adhesive, to provide anintermediate assembly. Then, a disc of the filter material may beprepared, and the disc of the filter material may be attached to thebottom of the intermediate assembly with, for example, an adhesive, toprovide a three-dimensional filter element 1050. Then the filter elementmay be inserted into aperture of the lower layer of the fluidicconnector 1110 and fixed onto the lower layer of the fluidic connector1110.

In some embodiments, a three-dimensional filter element may be placedwithin a wound dressing such as the wound dressing 100 described inrelation with FIG. 2B. In such embodiments, each an absorbent layer anda top film may be cut to create a hole. Then a spacer layer may beplaced on a wound contact layer sheet, followed by placement of theabsorbent layer. The three-dimensional filter element may be put inplace with the absorbent layer hole, and then the dressing may becovered by the top film sheet, in alignment with the hole of theabsorbent layer. Holes of the absorbent layer and the top film sheet maybe aligned for the fluidic connector attachment.

The three-dimensional filter element may be placed into the wounddressing in various methods. In some embodiments, such as shown in FIG.11A, a filter material may be cut into a thin strip and looped into atube, then slits may be cut into the top and bottom of the tube to formfoldable flaps 1172. Then the tube may be inserted into the aperture1180 of absorbent layer 1120 of the wound dressing, and the flaps may befolded and attached onto top and bottom side of the absorbent layer1120, for example with an adhesive 1175. Then two pieces of the filtermaterial 1173, for example in a square-shaped filter material, may covereach side of the tube. This assembly of the filter material and theabsorbent layer can be then placed on top of a spacer layer and under acover layer to form a wound dressing, and the fluidic connector 1110 maybe applied over the wound dressing.

In some embodiments, such as shown in FIG. 11B, a three-dimensionalfilter element may be constructed from multiple layers of the filtermaterial. The filter material may be cut into discs 1150, which will bestacked and placed within the aperture 1160 of the absorbent layer 1120.The filter material discs 1150 may not be fixed or attached, as they canbe contained within the area after a fluidic connector 1110 is attachedto the wound dressing 1100 and cover the aperture 1160.

While FIGS. 10A to 11B and associated descriptions have describedlocations of the three-dimensional filter within the NPWT system and howthe three-dimensional filter can be attached to the wound dressing orthe fluidic connector, these embodiments have been presented by way ofexample only, and locations of the three-dimensional filter within theNPWT system and method to provide and install the three-dimensionalfilter element are not limited by embodiments of FIGS. 10A-11B or anyother embodiments described elsewhere in the specification. Thethree-dimensional filter element may be placed in any suitable locationby any suitable methods so as to prevent the wound exudate from flowingout of the wound dressing. For example, the three-dimensional filter maybe placed above the wound dressing or next to the wound dressing.

Features, materials, characteristics, or groups described in conjunctionwith a particular aspect, embodiment, or example are to be understood tobe applicable to any other aspect, embodiment or example describedherein unless incompatible therewith. All of the features disclosed inthis specification (including any accompanying claims, abstract anddrawings), and/or all of the steps of any method or process sodisclosed, may be combined in any combination, except combinations whereat least some of such features and/or steps are mutually exclusive. Theprotection is not restricted to the details of any foregoingembodiments. The protection extends to any novel one, or any novelcombination, of the features disclosed in this specification (includingany accompanying claims, abstract and drawings), or to any novel one, orany novel combination, of the steps of any method or process sodisclosed.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of protection. Indeed, the novel methods and systems describedherein may be embodied in a variety of other forms. Furthermore, variousomissions, substitutions and changes in the form of the methods andsystems described herein may be made. Those skilled in the art willappreciate that in some embodiments, the actual steps taken in theprocesses illustrated and/or disclosed may differ from those shown inthe figures. Depending on the embodiment, certain of the steps describedabove may be removed, others may be added. Furthermore, the features andattributes of the specific embodiments disclosed above may be combinedin different ways to form additional embodiments, all of which fallwithin the scope of the present disclosure.

Although the present disclosure includes certain embodiments, examplesand applications, it will be understood by those skilled in the art thatthe present disclosure extends beyond the specifically disclosedembodiments to other alternative embodiments and/or uses and obviousmodifications and equivalents thereof, including embodiments which donot provide all of the features and advantages set forth herein.Accordingly, the scope of the present disclosure is not intended to belimited by the specific disclosures of preferred embodiments herein, andmay be defined by claims as presented herein or as presented in thefuture.

What is claimed is:
 1. A wound treatment apparatus comprising: a wounddressing comprising: a cover layer comprising an aperture; and anabsorbent layer comprising a recess extending vertically at leastpartially through a thickness of the absorbent layer, the absorbentlayer positioned beneath the cover layer; and a fluidic connectorcomprising an orifice, wherein the fluidic connector is configured toprovide negative pressure to the wound dressing through the orifice inthe fluidic connector and the aperture in the cover layer, wherein thefluidic connector comprises a sealing surface surrounding the orificeconfigured to seal the fluidic connector to the wound dressing; and athree-dimensional filter element configured to prevent wound exudatefrom exiting the wound dressing through the aperture of the cover layerwhen negative pressure is provided to the wound dressing, wherein thethree-dimensional filter element is adhered to an interior portion ofthe fluidic connector and extends from a wound dressing facing surfaceof the fluidic connector through the orifice of the fluidic connectorand through the aperture in the cover layer and extends vertically alongat least a portion of the thickness of the absorbent layer within therecess.
 2. The wound treatment apparatus of claim 1, wherein thethree-dimensional filter element spans the aperture in the cover layer.3. The wound treatment apparatus of claim 1, wherein the recess is athrough-hole which extends through the entire thickness of the absorbentlayer.
 4. The wound treatment apparatus of claim 1, wherein thethree-dimensional filter element is at least partially cylindricallyshaped or cuboid-shaped.
 5. The wound treatment apparatus of claim 1,wherein the three-dimensional filter element further comprises a filterlayer.
 6. The wound treatment apparatus of claim 5, wherein the filterlayer is oleophobic.
 7. The wound treatment apparatus of claim 5,wherein the three-dimensional filter element further comprises a spacercore, wherein the spacer core is at least partially enclosed by thefilter layer.
 8. A wound treatment apparatus comprising: a wounddressing comprising: a cover layer comprising an aperture; and anabsorbent layer positioned beneath the cover layer, the absorbent layerhaving a thickness; a fluidic connector comprising an orifice, whereinthe fluidic connector is configured to provide negative pressure to thewound dressing through the orifice in the fluidic connector and theaperture in the cover layer, wherein the fluidic connector comprises asealing surface surrounding the orifice configured to seal the fluidicconnector to the wound dressing; and a three-dimensional filter elementconfigured to prevent wound exudate from exiting the wound dressingthrough the aperture of the cover layer when negative pressure isprovided to the wound dressing, wherein the three-dimensional filterelement is adhered to an interior portion of the fluidic connector andextends from a wound dressing facing surface of the fluidic connectorthrough the orifice of the fluidic connector and through the aperture inthe cover layer.
 9. The wound treatment apparatus of claim 8, whereinthe three-dimensional filter element extends along at least a portion ofthe thickness of the absorbent layer.
 10. The wound treatment apparatusof claim 9, wherein the absorbent layer comprises a recess extendingvertically at least partially through a thickness of the absorbentlayer, and wherein the three-dimensional filter element extendsvertically along at least a portion of the thickness of the absorbentlayer within the recess.
 11. The wound treatment apparatus of claim 8,wherein the three-dimensional filter element is above the absorbentlayer.
 12. The wound treatment apparatus of claim 8, wherein thethree-dimensional filter element spans the aperture in the cover layer.13. The wound treatment apparatus of claim 8, wherein thethree-dimensional filter element is at least partially cylindricallyshaped or cuboid-shaped.
 14. The wound treatment apparatus of claim 8,wherein the three-dimensional filter element further comprises a filterlayer.
 15. The wound treatment apparatus of claim 14, wherein the filterlayer oleophobic.
 16. The wound treatment apparatus of claim 14, whereinthe three-dimensional filter element further comprises a spacer core,wherein the spacer core is at least partially enclosed by the filterlayer.
 17. The wound treatment apparatus of claim 1, wherein the fluidicconnector comprises a top layer and a lower layer, wherein the top layerand the lower layer are sealed to form the fluidic connector, whereinthe lower layer comprises a first side facing the top layer and anopposite second side.
 18. The wound treatment apparatus of claim 17,wherein the three-dimensional filter element comprises a flap portion,wherein the flap portion is configured to be located on the first sideof the lower layer.
 19. The wound treatment apparatus of claim 8,wherein the fluidic connector comprises a top layer and a lower layer,wherein the top layer and the lower layer are sealed to form the fluidicconnector, wherein the lower layer comprises a first side facing the toplayer and an opposite second side.
 20. The wound treatment apparatus ofclaim 19, wherein the three-dimensional filter element comprises a flapportion, wherein the flap portion is configured to be located on thefirst side of the lower layer.
 21. The wound treatment apparatus ofclaim 1, wherein the absorbent layer comprises a first wound facingsurface and an opposite second surface and wherein the three-dimensionalfilter comprises a first wound facing surface and an opposite secondsurface, wherein the three-dimensional filter comprises a first foldableflap coupled to the first wound facing surface of the three-dimensionalfilter and a second foldable flap coupled to the second surface of thethree-dimensional filter, wherein the first foldable flap is located ona first surface of the absorbent layer and the second foldable flap islocated on a second surface of the absorbent layer, and wherein thethree-dimensional filter extends vertically through the recess of theabsorbent layer.
 22. The wound treatment apparatus of claim 10, whereinthe absorbent layer comprises a first wound facing surface and anopposite second surface and wherein the three-dimensional filtercomprises a first wound facing surface and an opposite second surface,wherein the three-dimensional filter comprises a first foldable flapcoupled to the first wound facing surface of the three-dimensionalfilter and a second foldable flap coupled to the second surface of thethree-dimensional filter, wherein the first foldable flap is located ona first surface of the absorbent layer and the second foldable flap islocated on a second surface of the absorbent layer, and wherein thethree-dimensional filter extends vertically through the recess of theabsorbent layer.